The invention relates to a boot-retaining unit of a ski binding for securing one end, in particular the toe end, of a ski boot by way of two boot or sole holders which can be pivoted about vertical axes, engage around an end region of the sole periphery or of the ski boot from the side, front and/or top and interact with a spring arrangement, which biases the boot or sole holder against the boot or sole periphery and allows the ski boot to be disengaged counter to a disengaging resistance.
Such boot-retaining units are known in general. In the case of such a boot-retaining unit which is known from DE 25 13 456 A1, the sole holders are forcibly coupled to tooth segments which are arranged on them and mesh with one another, in which case they always assume similar positions. One of the sole holders is designed as a double-armed lever with a sole-side lever arm, which serves for securing the sole, and a lever arm which is remote from the sole and interacts with the spring unit, which is designed as a compression spring.
In the case of the boot-retaining unit which is known from DE 20 34 355 A1, the sole holders are designed as single-armed levers which, by means of a tension spring arranged between them, are biased into their normal position, in which the ski-boot sole is clamped in.
EP 0 626 875 B1 also discloses a boot-retaining unit with single-armed sole holders. Each sole holder is supported on an associated guide surface by means of a roller, the guide surface being arranged in each case on a double-armed lever, of which the arm which is remote from the guide surface interacts with the spring unit. It is thus possible for the guide surface, when subjected to sufficiently high loading by the roller, to yield counter to spring force, in which case the sole holders release the ski boot.
DE-A 1 578 702 discloses a boot-retaining unit with a single sole holder which engages around the toe of the boot in a C-shaped manner. This sole holder is guided such that it can be displaced transversely counter to spring force, the ski boot coming free when the sole holder is displaced sideways to a sufficient extent.
A similar boot-retaining unit is described in CH 686 707 A5. In this case, however, the sole holder, which engages around the toe of the boot in a C-shaped manner, is arranged such that it can be pivoted about a vertical axis and is coupled to a spring unit which is arranged beneath a boot-bearing surface and biases the sole holder into its normal position, in which the toe of the boot is secured.
EP 0 754 079 A1 also discloses a boot-retaining unit with a single sole holder which engages around the toe of the boot in a C-shaped manner, can be pivoted about a vertical axis and interacts with a spring arrangement provided beneath the boot-bearing surface.
The boot-retaining units of ski bindings are, generally, comparatively voluminous. This is not usually critical when the housings of the boot-retaining units are arranged in a stationary manner on the top side of the ski, as is typically the case for downhill skis. For cross-country skis, however, provision is usually made for the ski boot to be secured on a bearing plate which can be pivoted upward relative to the top side of the ski about a transverse axis on the toe region of the ski boot, in which case the heel can be lifted off from the ski for cross-country skiing purposes. There is only a comparatively small amount of space available in this case for boot-retaining units for securing the toe of the boot. Accordingly, cross-country ski bindings in which the toe of the boot is secured in sole holders which are stationary in relation to the bearing plate, and only disengagement of the heel of the boot is possible, are available on the market. This is synonymous with the boot-retaining unit which is arranged on the heel having to make it possible for the boot to be disengaged sideways in the event of a fall. Otherwise, it would not be possible for the boot to be detached from the ski in the event of a fall with turning action. Nevertheless, such a binding offers a reduced, albeit usually sufficient, level of safety in the event of the skier falling.